using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Windows.Forms;
using System.Net;
using System.IO;
  
class FtpClientForm : Form {
    public FtpClientForm() {
        InitializeComponent();
    }
  
    private string serverDirectory;
  
    private void OnOpen(object sender, EventArgs e) {
        Cursor currentCursor = this.Cursor;
        FtpWebResponse response = null;
        Stream stream = null;
        this.Cursor = Cursors.WaitCursor;
  
        FtpWebRequest request = (FtpWebRequest)WebRequest.Create(textServer.Text);
        request.Credentials = new NetworkCredential(textUsername.Text,
              textPassword.Text);
        request.Method = WebRequestMethods.Ftp.ListDirectory;
  
        response = (FtpWebResponse)request.GetResponse();
  
        stream = response.GetResponseStream();
        FillDirectoryList(stream);
  
        serverDirectory = null;
        buttonOpenDirectory.Enabled = false;
        buttonGetFile.Enabled = false;
  
        if (response != null)
            response.Close();
        if (stream != null)
            stream.Close();
        this.Cursor = currentCursor;
    }
  
    private void FillDirectoryList(Stream stream) {
        StreamReader reader = new StreamReader(stream);
        string content = reader.ReadToEnd();
        string[] files = content.Split('\\n');
        listFiles.DataSource = files;
        reader.Close();
    }
  
    private void OnOpenDirectory(object sender, EventArgs e) {
        FtpWebResponse response = null;
        Stream stream = null;
        string subDirectory = listFiles.SelectedValue.ToString().Trim();
        serverDirectory += @"/" + subDirectory;
        Uri baseUri = new Uri(textServer.Text);
        Uri uri = new Uri(baseUri, serverDirectory);
  
        FtpWebRequest request = (FtpWebRequest)WebRequest.Create(uri);
        request.Credentials = new NetworkCredential(textUsername.Text,
              textPassword.Text);
  
        request.Method = WebRequestMethods.Ftp.ListDirectory;
        response = (FtpWebResponse)request.GetResponse();
  
        stream = response.GetResponseStream();
        FillDirectoryList(stream);
        if (response != null)
            response.Close();
        if (stream != null)
            stream.Close();
    }
  
    private void OnDownloadFile(object sender, EventArgs e) {
        FtpWebResponse response = null;
        Stream inStream = null;
        Stream outStream = null;
        Uri baseUri = new Uri(textServer.Text);
  
        string filename = listFiles.SelectedValue.ToString().Trim();
        string fullFilename = serverDirectory + @"/" + filename;
  
        Uri uri = new Uri(baseUri, fullFilename);
  
        FtpWebRequest request = (FtpWebRequest)WebRequest.Create(uri);
        request.Credentials = new NetworkCredential(textUsername.Text,textPassword.Text);
        request.Method = WebRequestMethods.Ftp.DownloadFile;
        request.UseBinary = checkBoxBinary.Checked;
  
        response = (FtpWebResponse)request.GetResponse();
  
        inStream = response.GetResponseStream();
  
        saveFileDialog1.FileName = filename;
  
        if (saveFileDialog1.ShowDialog() == DialogResult.OK) {
            outStream = File.OpenWrite(saveFileDialog1.FileName);
            byte[] buffer = new byte[4096];
            int size = 0;
            while ((size = inStream.Read(buffer, 0, 4096)) > 0) {
                outStream.Write(buffer, 0, size);
            }
        }
  
        if (inStream != null)
            inStream.Close();
        if (outStream != null)
            outStream.Close();
        if (response != null)
            response.Close();
  
    }
  
    private void OnFileSelection(object sender, EventArgs e) {
        this.buttonGetFile.Enabled = true;
        this.buttonOpenDirectory.Enabled = true;
    }
    private void InitializeComponent() {
        this.label1 = new System.Windows.Forms.Label();
        this.textServer = new System.Windows.Forms.TextBox();
        this.buttonOpen = new System.Windows.Forms.Button();
        this.statusStrip1 = new System.Windows.Forms.StatusStrip();
        this.listFiles = new System.Windows.Forms.ListBox();
        this.buttonOpenDirectory = new System.Windows.Forms.Button();
        this.buttonGetFile = new System.Windows.Forms.Button();
        this.saveFileDialog1 = new System.Windows.Forms.SaveFileDialog();
        this.checkBoxBinary = new System.Windows.Forms.CheckBox();
        this.label2 = new System.Windows.Forms.Label();
        this.label3 = new System.Windows.Forms.Label();
        this.textUsername = new System.Windows.Forms.TextBox();
        this.textPassword = new System.Windows.Forms.TextBox();
        this.SuspendLayout();
        this.label1.AutoSize = true;
        this.label1.Location = new System.Drawing.Point(28, 31);
        this.label1.Size = new System.Drawing.Size(37, 13);
        this.label1.Text = "Server:";
        this.textServer.Location = new System.Drawing.Point(109, 31);
        this.textServer.Size = new System.Drawing.Size(146, 20);
        this.textServer.Text = "ftp://";
        this.buttonOpen.Location = new System.Drawing.Point(371, 31);
        this.buttonOpen.Size = new System.Drawing.Size(103, 23);
        this.buttonOpen.Text = "Open";
        this.buttonOpen.Click += new System.EventHandler(this.OnOpen);
        this.statusStrip1.LayoutStyle = System.Windows.Forms.ToolStripLayoutStyle.Table;
        this.statusStrip1.Location = new System.Drawing.Point(0, 0);
        this.statusStrip1.Size = new System.Drawing.Size(496, 18);
        this.statusStrip1.Text = "statusStrip1";
        this.listFiles.FormattingEnabled = true;
        this.listFiles.Location = new System.Drawing.Point(28, 149);
        this.listFiles.Size = new System.Drawing.Size(315, 160);
        this.listFiles.SelectedIndexChanged += new System.EventHandler(this.OnFileSelection);
        this.buttonOpenDirectory.Enabled = false;
        this.buttonOpenDirectory.Location = new System.Drawing.Point(371, 77);
        this.buttonOpenDirectory.Name = "buttonOpenDirectory";
        this.buttonOpenDirectory.Size = new System.Drawing.Size(103, 23);
        this.buttonOpenDirectory.TabIndex = 8;
        this.buttonOpenDirectory.Text = "Open Directory";
        this.buttonOpenDirectory.Click += new System.EventHandler(this.OnOpenDirectory);
        this.buttonGetFile.Enabled = false;
        this.buttonGetFile.Location = new System.Drawing.Point(371, 122);
        this.buttonGetFile.Size = new System.Drawing.Size(103, 23);
        this.buttonGetFile.Text = "Get File";
        this.buttonGetFile.Click += new System.EventHandler(this.OnDownloadFile);
        this.checkBoxBinary.AutoSize = true;
        this.checkBoxBinary.Checked = true;
        this.checkBoxBinary.CheckState = System.Windows.Forms.CheckState.Checked;
        this.checkBoxBinary.Location = new System.Drawing.Point(371, 190);
        this.checkBoxBinary.Size = new System.Drawing.Size(81, 17);
        this.checkBoxBinary.Text = "Binary Mode";
        this.label2.AutoSize = true;
        this.label2.Location = new System.Drawing.Point(28, 62);
        this.label2.Size = new System.Drawing.Size(54, 13);
        this.label2.Text = "Username:";
        this.label3.AutoSize = true;
        this.label3.Location = new System.Drawing.Point(28, 101);
        this.label3.Size = new System.Drawing.Size(52, 13);
        this.label3.Text = "Password:";
        this.textUsername.Location = new System.Drawing.Point(109, 62);
        this.textUsername.Size = new System.Drawing.Size(146, 20);
        this.textUsername.Text = "Anonymous";
        this.textPassword.Location = new System.Drawing.Point(109, 101);
        this.textPassword.PasswordChar = '?';
        this.textPassword.Size = new System.Drawing.Size(146, 20);
        this.textPassword.UseSystemPasswordChar = true;
        this.ClientSize = new System.Drawing.Size(496, 353);
        this.Controls.Add(this.textPassword);
        this.Controls.Add(this.textUsername);
        this.Controls.Add(this.label3);
        this.Controls.Add(this.label2);
        this.Controls.Add(this.checkBoxBinary);
        this.Controls.Add(this.buttonGetFile);
        this.Controls.Add(this.buttonOpenDirectory);
        this.Controls.Add(this.listFiles);
        this.Controls.Add(this.buttonOpen);
        this.Controls.Add(this.textServer);
        this.Controls.Add(this.label1);
        this.Text = "FTP Client";
        this.ResumeLayout(false);
        this.PerformLayout();
  
    }
    private System.Windows.Forms.Label label1;
    private System.Windows.Forms.TextBox textServer;
    private System.Windows.Forms.Button buttonOpen;
    private System.Windows.Forms.StatusStrip statusStrip1;
    private System.Windows.Forms.ListBox listFiles;
    private System.Windows.Forms.Button buttonOpenDirectory;
    private System.Windows.Forms.Button buttonGetFile;
    private System.Windows.Forms.SaveFileDialog saveFileDialog1;
    private System.Windows.Forms.CheckBox checkBoxBinary;
    private System.Windows.Forms.Label label2;
    private System.Windows.Forms.Label label3;
    private System.Windows.Forms.TextBox textUsername;
    private System.Windows.Forms.TextBox textPassword;
    [STAThread]
    static void Main() {
        Application.EnableVisualStyles();
        Application.Run(new FtpClientForm());
    }
}
//该片段来自于http://www.codesnippet.cn/detail/2303201511957.html